Serum Levels of Select Micronutrients in Primigravida With Preeclampsia Versus Normotensive Counterparts: a Case-control Study at the Kenyatta National Hospital

Abstract

Background: Preeclampsia is a multisystem disorder of unknown etiology that is unique to pregnancy. It remains to be one of the leading causes of maternal mortality as well as morbidity and long-term disability to mothers and newborns in sub-Saharan Africa. The status of serum levels of calcium, zinc and selenium as well as vitamin D has been implicated in the pathogenesis of preeclampsia. Indeed calcium supplementation is now recommended for its prevention in low-income settings. However, the supplementation of the other micronutrients remains debatable. This study looked into serum quantities of calcium, selenium, zinc and Vitamin D in women with preeclampsia compared to that of normotensive women in our setup. The findings of this study help to acknowledge these mineral deficiencies as part of the risk factors for preeclampsia in our population and subsequently recommend their supplementation as a preventive measure and encourage dietary changes. Broad Objective: To investigate the serum levels of select micronutrients (Vitamin D, calcium, zinc, and selenium) in preeclamptic and normotensive primigravid women Methods: Study design: This was a case-control study in which 54 primigravida with preeclampsia (cases) were compared with 54 primigravida who were normotensive (controls) and were matched for gestation and age. Study setting: Kenyatta National Hospital is a regional Teaching and Referral hospital with 1800 bed capacity. It has a busy reproductive health department that conducts 20-50 deliveries per day. The prevalence of preeclampsia in this institution is 5%.

Study population: A hundred and eight primigravid women comprised the study population. These included primigravida with preeclampsia ≥ 20 weeks gestation who were compared with their normotensive counterparts matched for gestation and age. These were 54 cases and 54 controls matched for age at ±2 years and gestational age of ± 2 weeks. Data collection procedures: After approval from the Kenyatta National Hospital/University of Nairobi-Ethics/Review Committee (KNH/UON-ERC) and seeking permission from the hospital administration, primigravida with preeclampsia, cases, as well as the normotensive controls were consented. They were then interviewed and had their demographic, obstetric parameters and dietary habits recorded in data collection sheets and blood samples obtained from them for determination of serum calcium, selenium, zinc and Vitamin D levels. The blood taken was put in specimen bottles with a serum separator gel and taken to a diagnostic laboratory in Nairobi for analysis. Data management and analysis: Data on demographic, obstetric and biochemical parameters, consumption of specific nutrient rich foods was coded entered into SPSS version 20. Means of the biochemical parameters were obtained for the two groups and compared using the Students T test, a P value of <0.05 was considered statistically significant. Chi square and the Fisher‟s exact test were used for categorical data. Results: A hundred and eight participants were included in this study (54 cases and 54 controls). Seventy-two percent of these women were between ages 20-30 years. Most, 90% had attained at least secondary education with an almost half and half distribution between the cases and the controls. Sixty-one percent of the study population had an average income of less that Ksh 10,000. The average gestational age was 35.2 ±4.4 weeks for the cases and 35.4±4.4 weeks for the controls. For the cases, 38.9% had preeclampsia without features of

severity (formerly mild preeclampsia) while 61.1% had severe preeclampsia. The average systolic and diastolic blood pressure among the cases was 155.7±17.4 and 105 ±10.2 respectively. Vitamin D deficiency was recognized in 31% of the entire study population. The distribution of these women with Vitamin D deficiency was such that 50% of those with preeclampsia were deficient compared to 27% normotensive women (p<0.001). The mean serum vitamin D level amongst cases and controls was 20.8±10.2 ng/ml and 28.6±7.9 ng/ml respectively (p<0.001). Serum calcium levels were 2.2±0.3mmol/l for the cases and 2.3±0.09mmol/l for the controls (p=0.024). We did not find statistically significant association between Selenium and Zinc with preeclampsia. Most of the controls consumed diets rich in calcium in comparison to the cases. Conclusion: Pregnant women with preeclampsia have lower serum levels of calcium and vitamin D, and are less likely to consume specific foods rich in these micronutrients. There is no association between serum level of selenium and zinc and preeclampsia. Recommendations: Calcium and vitamin D supplementation for pregnant women thought to be deficient in these micronutrients or who are at risk of preeclampsia is recommended. Pregnant women should receive nutritional advice to encourage deliberate consumption of locally available foods known to be rich in these micronutrients such as milk, natural yoghurt, green vegetables, fish and eggs.